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What Causes Sharp Knee Pain?

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Sharp knee pain symptoms are often a sign of a serious knee injury. Learn about the causes of severe knee pain and treatment options for stabbing knee pain.

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Sharp knee pain symptoms

The knee is the largest and most stressed joint in the human body. It is used in every movement — walking, jumping, running, even standing — and as a result, the knee is extremely vulnerable to injury. Most people, regardless of age, experience knee pain at some point in their lives. Older individuals may experience knee pain and discomfort due to multiple age-related conditions, and younger individuals may experience similar symptoms due to sports or other physical activities. However, sharp knee pain symptoms are often a sign of serious knee injury, and you should see a physician immediately.

Common accompanying symptoms of sharp knee pain

Symptoms often associated with sharp knee pain may include:

  • Swelling
  • Stiffness
  • Redness: Or warmth to the touch
  • Inability to fully extend or flex the knee
  • Inability to bear weight on the knee
  • Sensation of instability: Or "giving out" of the knee
  • Popping noises upon movement
  • Visible deformity

Sharp knee pain causes

Knee function and anatomy

The knee is a complex system of bones, cartilage, ligaments, tendons, and muscles responsible for weight-bearing and movement. See this image for a visual representation of these many components and how they connect. Any situation or condition that causes stress, inflammation or injury to any of these components can result in sharp knee pain.

  • Bones: The bones of the knee include the femur (thigh bone), patella (kneecap), and tibia (shin bone). The knee joint works to keep these bones securely in place.
  • Cartilage: The two types of cartilage in the knee are the minuscular cartilage and the articular cartilage. The cartilage act as cushions around the bones of the knee that reduce friction during movement, and help the bones move smoothly against each other. There is a medial meniscus on the inner side of the knee and a lateral meniscus on the outer side of the knee.
  • Ligaments: The knee has four ligaments that connect bones to other bones and promote stability: medial collateral, lateral collateral, posterior cruciate, and anterior cruciate ligaments. These ligaments prevent the side-to-side movement of the femur as well as excessive backward and forward movement of the femur and tibia.
  • Tendons: The tendons are similar to the ligaments and connect bone to muscle. The patellar tendon is the largest and attaches to the quadriceps.
  • Joint capsule and bursa: The joint capsule and bursa are fluid-filled membranes that lubricate the joint and reduce friction.

Musculoskeletal causes

Musculoskeletal causes of sharp knee pain may include the following.

  • Ligament: Ligament injury in the form of sprains and tears is very common in sports, especially those that combine running with contact such as soccer, football, and rugby. Injury to the ligaments results in loss of stability and severe knee pain symptoms that often require surgery.
  • Cartilage: Tears of the knee cartilage can occur when the knee twists while weight-bearing. These tears often occur during sports.
  • Fracture: The various bones of the knee can be broken during car accidents and serious falls. In older people or individuals with weak bones, fractures can occur after trips or missteps.
  • Mechanical: Problems with how the parts of the knee work together can result in sharp knee pain. Conditions such as Iliotibial band syndrome or dislocations of the kneecap often result in pain with movement.

Inflammatory causes

Inflammatory causes of sharp knee pain may include the following.

  • Arthritis: Arthritis is a general term for multiple conditions that cause painful inflammation and stiffness of the bones and joints. Arthritis can affect the bones and fluid-filled areas of the knee, resulting in significant irritation that can cause chronic and debilitating knee pain.
  • Infection: The knee is susceptible to scrapes and cuts that easily allow bacteria to enter into the joint space. These infections can cause serious swelling, pain, and redness of the knee.

This list does not constitute medical advice and may not accurately represent what you have.

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Prepatellar bursitis

Prepatellar bursitis is an inflammation of a fluid-filled sac (bursa) located in front of the knee (prepatellar) that normally acts as a cushion to help reduce friction. It can be caused by prolonged kneeling, such as for work, or due to injury or infection, and can either be acute or chronic. Symptoms of acute pre include warmth, redness, swelling, and pain at the front of the knee. If there is a cut near the knee or a fever, the bursa could be infected. Chronic pre may include symptoms such as a soft, painless lump at the front of the knee.

Patellofemoral pain syndrome

Patellofemoral pain syndrome (PFPS) is also called runner's knee, jumper's knee, anterior knee pain, chondromalacia patella, and patellofemoral joint syndrome.

Overuse through training for sports is a common cause, especially if there is a misalignment in the knee joint or a previous knee injury. This wears away the cartilage beneath the kneecap and causes pain on exercising.

It is most common in females and in young adults who are active in sports, but can affect anyone.

Symptoms include dull pain at the front of the knee and around the kneecap (patella) while running, squatting, or climbing stairs, or after prolonged sitting with knees bent.

Diagnosis is made through physical examination and through x-rays, CT scan, and/or MRI.

Treatment most often involves rest; over-the-counter pain relievers; low-impact exercise such as swimming or bicycling; physical therapy to strengthen and stabilize the knee; and orthotics (shoe inserts) to help correct a misaligned stride.

Surgery is needed only for severe cases, and is done through arthroscopy to remove any fragments of damaged cartilage.

Rarity: Common

Top Symptoms: knee pain, pain in one knee, knee pain that gets worse when going up stairs, dull, achy knee pain, knee pain that gets worse when squatting

Symptoms that always occur with patellofemoral pain syndrome: knee pain

Urgency: Primary care doctor

Meniscal injury

The menisci are the two pieces of cartilage serving as shock absorbers in the knee, between the lower end of the thighbone and the top of the shinbone. A torn meniscus is commonly referred to as "torn cartilage" in the knee.

Damage to a meniscus often happens along with another injury to the knee, especially when there is any forceful, twisting movement or a direct hit such as a tackle.

Older people may tear a meniscus through normal activity if the cartilage has become thin and worn due to aging.

Symptoms include pain, stiffness, and swelling. The knee will simply not work correctly and may catch, lock up, or give way.

Diagnosis is made through patient history, physical examination, simple motion tests, and imaging such as x-ray or MRI.

Depending on the exact form of the injury, the tear may be allowed to heal on its own with supportive care such as rest, ice, and nonsteroidal anti-inflammatory pain medication. In other cases, arthroscopic surgery followed by rehabilitation may be needed.

Rarity: Common

Top Symptoms: pain in one knee, knee stiffness, knee instability, pain in the inside of the knee, swollen knee

Urgency: Primary care doctor

Knee arthritis

Knee arthritis means that there is inflammation and abnormal wear of one or both of the two joints in the knee.

Arthritis in any joint is most often be caused by long-term wear and tear, called osteoarthritis; by an autoimmune condition that attacks the joints, called rheumatoid arthritis; or by an injury, called post-traumatic arthritis.

Symptoms include pain, which becomes worse with use of the joint; limited range of motion, meaning the shoulder joint cannot move as far as it once did; and pain when resting or trying to sleep.

Knee arthritis cannot be cured, but symptoms can be managed to improve quality of life and ease pain and discomfort.

Diagnosis is made through patient history, physical examination, and x-rays. To confirm, an injection of anesthetic may be placed into the joint. If the pain is eased, arthritis is almost certainly the cause.

Treatment involves physical therapy; nonsteroidal anti-inflammatory drugs to ease discomfort and inflammation; and corticosteroid injections into the knee to relieve pain. Surgery and knee joint replacement can be done in some cases.

Rarity: Common

Top Symptoms: pain in both knees, knee stiffness, knee instability, swollen knee, morning joint stiffness

Symptoms that always occur with knee arthritis: pain in both knees

Urgency: Primary care doctor

Jumper's knee (patellar tendonitis)

Jumper's knee is also called patellar tendinitis or patellar tendinopathy. It is an inflammation of the patellar tendon, which runs from the bottom of the patella – or kneecap – to the top of the shinbone.

It is most often an overuse injury seen in athletes, especially those in sports involving jumping, but it can affect anyone. Strenuous physical activity without warming up first, or tightness and inflexibility in the muscles of the thighs, can put additional strain on the patellar tendon.

Symptoms include pain just below the kneecap. At first it may only appear during exercise, but later becomes chronic as the tendon becomes more damaged and inflamed. Eventually the pain interferes with normal movement.

It is important to get treatment, as the condition will not heal on its own and will only get worse through forced movement.

Diagnosis is made through patient history, physical examination, and imaging such as ultrasound or x-ray.

Treatment involves rest; pain relievers; physical therapy to return flexibility to the tendon; and sometimes corticosteroid injections or surgery.

Rarity: Rare

Top Symptoms: pain in one knee, spontaneous knee pain, knee pain that gets worse when going up stairs, knee stiffness, knee pain that gets worse when squatting

Urgency: Primary care doctor

Infrapatellar bursitis

Infrapatellar bursitis is an inflammation of the bursa, or small cushioning sacs, beneath the patella, or kneecap. The condition may affect either the superficial bursa or the deep bursa.

Superficial infrapatellar bursitis is found in those whose work requires them to kneel on hard surfaces, and so it is known as housemaid's knee, clergyman's knee, parson's knee, or vicar's knee.

Deep infrapatellar bursitis can occur from chronic overuse, as with sports training and other hard physical work.

Either form of the condition can also be caused by hemorrhage, infection, traumatic injury, or inflammatory diseases such as arthropathy. Some cases may be idiopathic, meaning they occur in a particular individual for no clear reason.

Symptoms include swelling of the knee and pain below the kneecap.

Diagnosis is made through patient history and physical examination as well as x-ray, CT scan, or MRI.

Treatment involves rest; heat; nonsteroidal anti-inflammatory drugs to reduce pain and swelling; a knee brace; and sometimes corticosteroid injections into the knee.

Rarity: Uncommon

Top Symptoms: pain in one knee, spontaneous knee pain, dull, achy knee pain, knee pain that gets worse when going up stairs, knee pain that gets worse when squatting

Urgency: Self-treatment

Iliotibial (IT) band syndrome ('runner's knee')

Iliotibial band syndrome is also called ITBS or IT syndrome. The iliotibial band is a long, thick piece of connective tissue that begins at the top of the hip bone, runs down the outside of the leg, and attaches at the side of the knee.

ITBS is an overuse syndrome. Athletes in heavy training are susceptible to it, especially runners and cyclists. Pain and inflammation result if the far end of the iliotibial band constantly rubs against the outside of the knee joint.

Symptoms include pain on the outside of the knee, especially while running or while sitting with the knee flexed.

Diagnosis is made through patient history and physical examination, with simple stretching tests to identify the exact location of the pain. An MRI is sometimes ordered.

Treatment involves rest; ice; over-the-counter nonsteroidal anti-inflammatory drugs; stretching exercises for the iliotibial band; strengthening of the upper leg muscles; and, if needed, changes in the way the person strides or trains. Corticosteroid injections can be helpful and surgery may be tried in some cases.

Rarity: Common

Top Symptoms: knee pain, pain in one knee, dull, achy knee pain, knee pain that gets worse when going down stairs, sharp knee pain

Symptoms that always occur with iliotibial (it) band syndrome ('runner's knee'): knee pain

Urgency: Primary care doctor

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Fibromyalgia is a set of chronic symptoms that include ongoing fatigue, diffuse tenderness to touch, musculoskeletal pain, and usually some degree of depression.

The cause is not known. When fibromyalgia appears, it is usually after a stressful physical or emotional event such as an automobile accident or a divorce. It may include a genetic component where the person experiences normal sensation as pain.

Almost 90% of fibromyalgia sufferers are women. Anyone with rheumatic disease, such as rheumatoid arthritis or lupus, may be more prone to fibromyalgia.

Poor sleep is often a symptom, along with foggy thinking, headaches, painful menstrual periods, and increased sensitivity to heat, cold, bright lights, and loud noises.

There is no standard test for fibromyalgia. The diagnosis is usually made when the above symptoms go on for three months or more with no apparent cause.

Fibromyalgia does not go away on its own but does not get worse, either.

Treatment involves easing symptoms and improving the patient's quality of life through pain medications, exercise, improved diet, and help with managing stressful situations.

Rarity: Common

Top Symptoms: fatigue, arthralgias or myalgias, anxiety, depressed mood, headache

Symptoms that always occur with fibromyalgia: arthralgias or myalgias

Urgency: Primary care doctor

Dislocated kneecap

The kneecap connects the muscles in the front of the thigh to the shinbone (tibia). When the slips out of the groove, problems and pain often result.

You should visit your primary care physician within the next 24 hours. The first step is to return the kneecap to its proper place, a process called reduction.

Knee bursitis (pes anserine bursitis)

Pes anserinus means "goose's foot. In this case it refers to the appearance of the three pes anserinus tendons which lie together at the inside of the knee, about two inches below the level of the kneecap.

Pes anserine bursae are small cushion-like structures which lie between the tibia, or shinbone, and the pes anserinus tendons. Inflammation of these bursae is called pes anserine bursitis.

Bursitis is most often caused by overuse. Pes anserine bursitis is found in runners, especially when training without sufficient warmup. It can also occur where there is osteoarthritis of the knee; a knee that turns outward; or obesity.

Symptoms include pain, tenderness, and swelling of the bursa, especially with climbing stairs or other exercise.

Diagnosis is made through physical examination and x-ray.

Treatment involves rest; ice; nonsteroidal anti-inflammatory drugs for pain and swelling; physical therapy; and sometimes corticosteroid injections into the injured bursa. Surgery may be done if conservative measures do not help.

Rarity: Common

Top Symptoms: pain in one knee, knee pain that gets worse when going up stairs, spontaneous knee pain, knee pain that gets worse when going down stairs, knee pain that gets worse when standing up

Symptoms that always occur with knee bursitis (pes anserine bursitis): pain in one knee

Urgency: Self-treatment

Sharp knee pain treatments and relief

When to see a doctor

Severe knee pain requires professional medical attention. Treatment depends on the specific diagnosis and may include one or all of the following:

  • Physical therapy: After many knee injuries, your doctor will suggest physical therapy to restore range of motion, strength, and stability to your knee.
  • Medication: If your severe knee pain is due to inflammatory conditions, your doctor may prescribe antibiotics to treat an infection or anti-inflammatory medications to treat arthritic conditions.
  • Surgery: Fractures and tears of the ligaments and cartilage of the knee often require surgical intervention but often have great success.


There are many measures you can take in your daily life to prevent knee injury and severe pain, such as the following.

  • Maintain a healthy weight: The knees bear all of the body's weight, so extra pounds can cause unnecessary stress and strain, increasing risk of injury.
  • Be strong and flexible: The quadriceps and hamstring muscles provide support to the knee joint, so keeping them strong, conditioned, and flexible will benefit the functioning of the knee as a whole.
  • Practice technique: If you participate in competitive sports and practice often, ensure that your techniques and movements are not putting unnecessary stress on your knees. Work with a coach to ensure that when you run, jump or move side-to-side, your knee is in the best position to prevent injury.
  • Listen to your body: If you find yourself experiencing mild or transient knee pain after certain activities, listen to your body and take a break! Rest, ice and elevate your knee once you first notice sharp knee pain symptoms and make an appointment with your doctor promptly.

Questions your doctor may ask about sharp knee pain

  • Is the knee pain affecting one or both knees?
  • Where is your knee pain?
  • How would you explain the cause of your knee pain?
  • Do you often feel your knees buckling?

Self-diagnose with our free Buoy Assistant if you answer yes on any of these questions.

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Dr. Rothschild has been a faculty member at Brigham and Women’s Hospital where he is an Associate Professor of Medicine at Harvard Medical School. He currently practices as a hospitalist at Newton Wellesley Hospital. In 1978, Dr. Rothschild received his MD at the Medical College of Wisconsin and trained in internal medicine followed by a fellowship in critical care medicine. He also received an MP...
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